1. Technical Field
The disclosure relates to backlight driving systems, and particularly to a multi-lamp driving system.
2. Description of Related Art
A plurality of cold cathode fluorescent lamps (CCFL) are usually used as a backlight of a liquid crystal display (LCD). In order to light the plurality of CCFLs, an inverter is needed to convert input power into alternating current (AC) power to provide suitable driving power. The inverter includes a plurality of transformers, each of which drives one or two CCFL. If primary windings of the plurality of transformers are connected in parallel, the plurality of the transformers need high leakage inductance to maintain current balance among the plurality of CCFLs. However, the plurality of transformers with high leakage inductance result in high temperature rise and large sizes.
If the primary windings of the plurality of transformers are connected in series, the plurality of transformers with low leakage inductance can maintain current balance among the plurality of CCFLs. However, in this structure, voltage to drive one CCFL and voltage to drive two CCFLs are different, which may result in that driving voltage is not sufficient to driving the plurality of CCFLs or the plurality of transformers are burnt due to the high driving voltage.